1. Field of the Invention
The present invention relates to a printer, copier, facsimile apparatus or similar image forming apparatus of the type including a removable process cartridge or similar replaceable part. Also, the present invention relates to an image forming apparatus constructed to manage information particular to each replaceable part, which varies due to repeated operation, for thereby optimizing the operation of the individual replaceable part, and a replaceable part and an IC (Integrated Circuit) chip applicable thereto.
2. Description of the Background Art
In a printer or similar electrophotographic image forming apparatus, a photoconductive element, toner and so forth joining in an image forming process each are usable only for a preselected period due to wear and other causes. Such parts have customarily been constructed into replaceable process cartridges to be replaced by the user.
There is an increasing demand for an image forming apparatus implementing high image quality. As for an electrophotographic process, various devices have been proposed for high image quality in relation to process cartridges. A toner cartridge, for example, has a problem that toner density varies when the toner cartridge is new or approaches the end of the usable period. To solve this problem, toner in the toner cartridge is, e.g., agitated to uniform the toner density for thereby maintaining high image equality. To effect operation matching with instantaneous conditions of use, it is necessary to grasp the conditions of the individual toner cartridges and deliver information representative of the conditions, as needed. For this purpose, nonvolatile storing means may be built in each toner cartridge for storing, e.g., the condition of use of toner that varies due to a repeated image forming cycle. This allows operation specifications for maintaining high image quality to be determined in accordance with the stored data, thereby optimizing image forming conditions.
The cumulative number of prints output with a cartridge or replaceable part is one of data representative of the condition of use of the cartridge. The cumulative number of prints is written to storing means built in the cartridge. When the stored number of prints reaches a preselected number of prints, printing operation is effected with preselected specifications. For example, the fact that the stored number of prints has reached the preselected number of prints, i.e., the fact that the replaceable part has approached its limit of use is reported to a process controller or to the user.
Another requisite with an image forming apparatus is high-speed operation. Specifically, various devices have been proposed not only for increasing a print speed but also for reducing a first print time and a recovery time from an energy saving stand-by mode. The first print time refers to an interval between the power-on of the apparatus and the time when the apparatus outputs the first print. In the energy saving stand-by mode, the apparatus waits for an input while shutting off power supply to its sections other than a monitor section.
In a sense, however, the demand for high image quality and the demand for high-speed operation are contradictory to each other. Specifically, the extra operation of the apparatus for improving image quality, as distinguished from printing operation, extends an interval between the input of a print command and the output of a print. This obstructs high-speed operation and energy saving.
Assume that operation specifications are determined on the basis of management information, e.g., the condition of use of a cartridge for thereby optimizing image forming conditions, and that the management information is stored in storing means built in the cartridge, as stated earlier. Then, whether or not control for the optimization of image forming conditions is necessary or whether or not conditions set should be varied is determined in accordance with the information read out of the storing means. Such optimization is effected when an image is to be formed. More specifically, the optimization is part of initialization executed at the time of power-up or the recovery from the energy saving stand-by mode. Consequently, the optimization is apt to extend the first print time or the recovery time from the stand-by mode.
Technologies relating to the present invention are disclosed in, e.g., Japanese Patent Laid-Open Publication Nos. 8-69212, 10-52964 and 2000-172133.